presiding officer vs leader

presiding officer and leader both are nouns.

Word	Noun	Adjective	Verb	Adverb
presiding officer	Yes	No	No	No
leader	Yes	No	No	No

As nouns, leader is a hypernym of presiding officer; that is, leader is a word with a broader meaning than presiding officer:

presiding officer (noun)	leader (noun)
the leader of a group meeting	a featured article of merchandise sold at a loss in order to draw customers
	a person who rules or guides or inspires others